Federal authorities have cancelled Tuesday’s court hearing with Apple, saying an ‘outside party’ has shown a potential way to crack Syed Farook’s phone

Federal authorities have asked a California court to delay a hearing designed to force Apple into compromising its security systems for the iPhone, in an astonishing reversal by the US government.

On Monday, the justice department said it potentially had another way into the phone – something cryptographers, leading data security experts and even Edward Snowden have said was possible without placing the cybersecurity of all iPhone users at risk through creating what Apple derisively calls “GovtOS”.

The US justice department request – a day before a federal court was scheduled to hear arguments in a case that has attracted global attention over its implications for the future of encryption – comes after more than a month of heated insistence that the only way the FBI could examine a locked iPhone used by a terrorist was for Apple to write new software without some of its operating system’s security features.

A law enforcement official said Monday evening that the hearing Tuesday has been cancelled. A spokesman for the court couldn’t be reached.

US investigators said they have continued to look for new ways into the iPhone 5C used by San Bernardino gunman Syed Farook since the justice department took Apple to court. In 2014, Apple updated its iPhone software such that it could no longer download data from locked devices without the user’s passcode, which Apple doesn’t know.

The forensic standstill caused many to question the FBI’s technical chops. Many security experts offered possible ways the government may be able to get into Farook’s phone without Apple’s help.

On 20 March, the government said, an “outside party” showed the government a potential way to crack open Farook’s phone. The government said it would like to test the method and file a report with the court by 5 April.

An Apple spokesman didn’t immediately reply to a request for comment. The White House, which has stood by the justice department in its feud with Apple, didn’t immediately comment on the reversal.

On the one hand, the delay short-circuits a massive privacy battle between America’s most valuable company and its government that had been building for two years. National media were already descending Monday on southern California for the hearing in the federal courthouse in Riverside.

On the other, the government’s reversal seems to only postpone the inevitable. Both US officials and technology executives have said that if the San Bernardino case hadn’t brought the two sides into court, another one surely would.

Melanie Newman, a justice department spokeswoman, said the department was “cautiously optimistic” that the proposed new investigative tactic would work, but testing was required.

“If this solution works, it will allow us to search the phone and continue our investigation into the terrorist attack that killed 14 people and wounded 22 people,” Newman said in a statement.